Case Report
Narges Ghobadi, Nobuhiro Yu
Abstract
In this study, it was shown that how rheology and fluid dynamics effected the behavior of cell growth and L-Lactic acid productivity during cultivation of filamentous fungi (Aspergillus oryzae) in a stirred-tank. Submerged culture of A. oryzae was a shear-thinning fluid with complex rheology and morphology. It is a shear-sensitive fluid. The scope of this study, was enhancing the gas-liquid flow of fermentation fluid to improve the liquid-gas mass transfer, L-lactic acid production and stagnant zone reduction at low energy consumption by effective shear rate generation using multi-large blade agitator with global axial pattern of mixing. Due to this reason, the advantage of Fullzone® (FZ), and impeller was investigated. Experimental results when using multi-large and multi-radial impeller, showed that the same volumetric power consumption of the dissolved oxygen concentration, Re, macro and micro-morphology size, biomass and L-lactic acid production when using multi large impeller was higher and more stable than that of the multi radial impeller. Most of above positive properties were due to the reduction in viscosity and apparent consistence index of fermented fluid.